Pro Audio Reference (R)

R

radar (radio detecting and ranging) 1. A method of detecting distant objects and determining their position, velocity, or other characteristics by analysis of very high frequency radio waves reflected from their surfaces. 2. The equipment used in such detection. [AHD] Compare with sonar and sodar.

radian 1. Mathematics. A unit of angular measure equal
to the angle subtended at the center of
a circle by an arc equal in length to the radius of the circle, approximately
57°17'44.6 [AHD] 2. Filters. Frequency is measured in radians/second. One cycle (360°) equals 2π (pi) radians.

radiation error Loudspeakers. All inclusive term describing
the total lobing and cancellation error occurring in a loudspeaker response
due to crossover and multiple driver effects. An ideal crossover applied
between two sources would exhibit no lobing
error and no cancellations off axis. [Coined by Justin Baird and David
McGrath, Lake Technology, in their paper "Practical Application of Linear
Phase Crossovers with Transition Bands Approaching a Brick Wall Response
for Optimal Loudspeaker Frequency, Impulse and Polar Response," presented
at the 115th Convention of the Audio Engineering Society, New York, NY
October 10-13, 2003, Preprint
5885.]

radicalism "The conservatism of tomorrow injected into the affairs
of today." — Ambrose Bierce.

radio The wireless transmission through space of electromagnetic waves in the approximate frequency range from 10 kilohertz to 300,000 megahertz. [AHD]

radio buttonA graphical user interface style based on old automobile analog radio designs.

RadiolabBroadcast. Popular public radio program that describes itself this way: "Radiolab believes your ears are a portal to another world. Where sound illuminates ideas, and the boundaries blur between science, philosophy, and human experience. Big questions are investigated, tinkered with, and encouraged to grow. Bring your curiosity, and we'll feed it with possibility."

radixMathematics. The number base,
such as 2 in the binary system and 10 in the decimal system. [AHD]

radix point The binary equivalent of the decimal point — think
of it as a "binary point."

Ragone chart A useful way to compare such things as batteries, this chart plots storage device energy density versus power density on a log-log graph with discharge times represented as diagonal lines.

RAID(Redundant Array of Independent Disks) [Originally: Redundant Array of Inexpensive Disks] A technology providing greater storage functions and reliability using redundancy. Hit the link for details. Finding its way into pro audio studio use by such companies as Glyph's Portagig 62.

rail-switcher A term used to describe
audio power amplifier designs utilizing more than one power supply for
the output, and a means of switching between them based upon the input
signal. This scheme improves efficiency. See Class
G Amplifiers and compare with tracking
power amplifiers.

rail-to-rail® Registered
trademark of Nippon Motorola, Ltd. for their op amp designs having maximum
input and output levels equal to the power supply voltages. See RRIO.

rainstickMusical Instrument. English translation for the original Chilean instrument called palo de lluvia.

raised cosine filter A low-pass
filter found most often in data communication systems. A perfect raised
cosine filter is characterized by a frequency response that is symmetrical
about 0 Hz, with a flat low frequency passband,
then a smooth rolloff following a cosine curve to zero through the transition
region and staying at zero (infinite attenuation) throughout the stopband.
The response of real world filters (usually DSP FIR designs) approximate this response, with the most noticeable deviation
being ripple in the transition region, limiting attenuation to, say, 70
dB, or so, depending on the number of filter taps used. The first known
use of this technology in pro audio occurred with a proprietary filter
based on raised cosine design used in the Lake
Contour™ system.

RAM (random access memory) A memory
device in which data may be read out and new data written into any address
or location.

Ramone, Phil(1934-2013) Famous American record producer and recording engineer, who worked with the biggest stars.

Randall, Don (1917-2008) American entrepreneur who cofounded Fender in 1946 along with Leo Fender. Beginning in the 1970s he started his own company using the Randall brand.

RaneNotes A series of technical notes
written by Rane's technical staff.

RaneWare® A registered trademark of Rane Corporation used to identify Rane RW
232 software products — not something to keep you dry.

Rankine scale A scale of absolute temperature using degrees the
same size as those of the Fahrenheit scale, in which the freezing point
of water is 491.69° and the boiling point of water is 671.69°.
After William John Macquorn Rankine below. [AHD. Sounds handy to me.]

RAQ (rarely asked questions) The really important questions
that should be asked, but never are. The answers to RAQs are kept hidden
within government and corporate walls.

rarefaction 1. A decrease in density
and pressure in a medium, such as air, caused by the passage of a sound
wave.2. The region in which this occurs. [AHD]

RASTI (room acoustics speech transmission index) [Originally spelled RaSTI, with lower-case a, which was an acronym for rapid speech transmission index.] A speech intelligibility performance technique developed in 1973 by Dr. Steeneken in Holland, it is simpler
than the more complex STI(speech transmission index), however overtime this procedure proved unreliable and was removed as a IEC standard with the 2011 revision to IEC 60268-16.
Compare with %ALCONS.

rationalism 1. Reliance on reason as the best guide for belief and action. 2. Philosophy The theory that the exercise of reason, rather than experience, authority, or spiritual revelation, provides the primary basis for knowledge. [AHD] [The optimist says the glass is half full. The pessimist says the glass is half empty. The rationalist says the glass is twice as big as it needs to be.]

Rayleigh distance Acoustics. "The geometric nearfield of a finite acoustic radiator is the area around the radiator where the sound pressure level does not follow spherical or cylindrical spreading ... The Rayleigh distance D = ka²/2, where k = 2pi f/c, f is the frequency, c is the sound speed, and a is half the largest dimension, has been used to approximate the size of the geometric nearfield of plane radiators." From Kuntz, Hixson and Ryan, "The Rayleigh distance and geometric nearfield size of nonplane sound radiators," Jour. Acoust. Soc. Amer., Nov., 1983.

Rayleigh, Lord (1842-1919), Third Baron. Title of John William Strutt. British physicist. He won a 1904 Nobel Prize for investigating the density of gases and for discovering argon with Sir William Ramsay.

Rayleigh scatteringPhysics. The scattering of electromagnetic radiation by particles with dimensions much smaller than the wavelength of the radiation, resulting in angular separation of colors and responsible for the reddish color of sunset and the blue of the sky. [AHD]

RC (room criteria) rating A new noise
criteria adopted by ASHRAE to replace the NC criteria. The RC rating is based
on ASHRAE sponsored studies of preference and requirements for speech privacy
ratings for "acoustical quality." RC ratings contain both a numerical value
and a letter to describe the expected spectral quality of the sound. The
numerical part is called the speech interference level (SIL) equal to the arithmetic average of the measured SPL in the 500 Hz, 1 kHz
and 2 kHz octave bands, and the letter part denotes the timbre or sound quality as subjectively described by an observer as neutral
(N), rumbly (R), hissy (H) or acoustically induced vibration noise (RV).
The RC curves serve as optimum spectrum shapes for background sound in
buildings. Octave band analysis that meet a specific RC curve are considered neutrally balanced, i.e., they have the desired amounts of low-,
mid- and high-frequency content to be heard as not offensive. RC curves
are straight lines set at -5 dB/octave slopes (of course — couldn't
be 6, had to be 5). The RC rating standard is Criteria for Evaluating
Room Noise, ANSI S12.2.

RCDDTM (Registered Communications Distribution Designer) A designation
for individuals who demonstrate expertise in the design, integration, and
implementation of telecommunications (voice, data, video, audio, and other
low-voltage control) transport systems and their related infrastructure
components.

RC time constantElectronics. One time constant equals the time required for the output voltage to increase to 63%, or decrease to 37%, of the final value, due to a step input voltage change. This action is fundamentally controlled by a resistor-capacitor pair. [Although not obvious, time (in seconds) equals resistance (in ohms) times capacitance (in farads).]

R-DAT or DAT (rotary head digital
audio tape recorder) A digital audio recorder utilizing a magnetic
tape cassette system similar to that of a video recorder.

reamplifying Originally this term meant to take an already recorded
guitar sound and use it to drive another different sounding guitar amp — literally reamplifying it as a means of changing the original recorded
sound. Now used on any recorded sound with a real amplifier or virtual
plug-in.

rearaxial softspeaker Term
coined by Electro-Voice for their mythical loudspeaker, the SP13.5TRBXWK.
Claimed by many to be the speaker that couldn't be made, it might have
changed all future loudspeaker design, but it didn't. Characterized by
being undirectional, the designer's claimed it produced silken highs and
woolen lows. The only loudspeaker known to incorporate both "presence" and "absence" controls. Based on a ridiculously simple principle
that still cannot be explained, the SP13.5TRBXWK was only heard once, during
the Rane demo of their PI 14 Pseudoacoustic
Infector, coupled by a Jensen JE-EP-ERs
Multi-denomial Transpedance Informer to a Crown Belchfire
BF-6000SUX amplifier. No one survived.

rear lobe Microphones. A region of pickup at the rear of a supercardioid or hypercardioid microphone polar pattern. A bidirectional microphone has a rear lobe equal to its front pickup. [Vear]

rebab Musical Instrument. A type of bowed or plucked string instrument indigenous to the Middle East.

reconstruction filter A low-pass filter used at the output of
digital audio processors (following the DAC)
to remove (or at least greatly attenuate) any aliasing products (image spectra present at multiples of the sampling frequency)
produced by the use of real-world (non-brickwall) input filters.

rectifier An electronic component used
to convert from alternating current (AC) to direct-current (DC). Works
by only conducting current in one direction which allows inversion or suppression
of alternate half cycles. Several types exist from early selenium
rectifiers to modern semiconductor diodes.
See full-wave and half-wave.

recursive 1. A data structure that is defined in terms of itself.
For example, in mathematics, an expression, such as a polynomial, each
term of which is determined by application of a formula to preceding terms.
[AHD] 2. Pertaining to a process that is defined
or generated in terms of itself, i.e., its immediate past history. 3. Use of feedback as in a recursive filter.

Red Book Nickname for the Philips and
Sony's ECMA-130 standard document that defines the format for CD-Audio
(compact disc-digital audio) discs; available only to licensees. Compare
with Green Book and Yellow
Book.

RedfestDXB The biggest Middle East music festival, held yearly in Dubai. Winner of Time Out magazine's Music and Nightlife Awards in 2015.

reed Music. 1. A primitive wind instrument made of a hollow reed stalk. 2.
a. A flexible strip of cane or metal set into the mouthpiece or air opening of certain instruments to produce tone by vibrating in response to a stream of air. b. An instrument, such as an oboe or clarinet, that is fitted with a reed. [AHD]

REED (Record Engineering Development Department) EMI lab responsible for the famous recording console used to record the Beatles at Abbey Road Studios.

reed organMusical Instrument. An organ design using reeds rather than pipes.

reed relay Electronics. A relay using glass-enclosed, magnetically closed reeds as the contact members. Some forms are mercury-wetted.

reentrant loudspeaker Reentrant means directed inward. A reentrant loudspeaker is a folded horn design where the sound does not radiate forward from a cone but is routed forward than back to a bell which directs it forward again. This design achieves very loud SPL in a small size and is popular for public address use where loud SPL is required to overcome background noise. Hit the link and scroll down to see a great diagram and picture of a reentrant horn.

relay Electronics. An electromechanical device with a coil that when energized creates a magnetic field that either opens or closes metal contacts, for making or breaking electrical connections. Invented by Joseph Henry in 1835.

reluctance Magnetics. A measure
of the opposition to magnetic flux, analogous to electric resistance. [AHD]

R.E.M. (Remember Every Moment) Music. Athens, Georgia band formed in 1980
by Michael Stipe, Mike Mills, Bill Berry, and Peter Buck. Upon being inducted into the Rock and Roll Hall of Fame in 2007, Michael Stipe disclosed that the band's name came from a favorite saying of his mother.

remixing DJ Recording. An alternate variation of one or more original song (or video, etc.) compositions created by manipulating the original using various recording techniques to create a new version.

REO Speedwagon Music. American rock group formed in 1967. REO Speedwagon took
its name from the Reo
Speed-Wagon, a truck manufactured by the REO automobile company. ("REO" are initials the company's founder, Ransom Eli Olds, who also lent his name to the Oldsmobile division of General Motors.)

residual 1. The quantity left over at the end of a process; a remainder. 2. often residuals A payment made to a performer, writer, or director for each repeat showing of a recorded television show or commercial. [AHD]

residual sound Acoustics. The all-encompassing sound , at a specified time, being usually a composite of sound from many sources at many directions, near and far, remaining at a given position in a given situation when all uniquely identifiable discrete sound sources are eliminated, rendered insignificant, or otherwise not included. [Harris]

resistivity Symbol ρ (Greek letter small rho). Electricity.
An intrinsic property of a material that is measured as its resistance
to current per unit length for a uniform cross section. [AHD]

resistorElectronics. Circuit symbol: R 1. An element within a circuit that has specified resistance value designed to restrict the flow of current. 2. A device with the primary purpose of introducing resistance into an electric circuit. (A resistor as used in electric circuits for purposes of operation, protection, or control, commonly consists of an aggregation of units. Resistors, as commonly supplied, consist of wire, metal, ribbon, cast metal or carbon compounds supported by or embedded in an insulating medium. The insulating medium may enclose and support the resistance material as in the case of the porcelain tube type or the insulation may be provided only at the points of support as in the case of heavy duty ribbon or cast iron grids mounted in metal frames.) [IEEE] See: color-code and standard component values.

resonance 1. Electronics. In an LRC circuit,
it is the condition where the inductive and capacitive reactances are equal; this is called the
resonant frequency. 2. Physics. The increase in amplitude of oscillation
of an electric or mechanical system exposed to a periodic force whose frequency
is equal or very close to the natural undamped frequency of the system.
[AHD] A dynamic condition which occurs
when any input frequency of vibration coincides with one of the natural
frequencies of the structure. That is, the inclination of any mechanical
or electrical system to vibrate (resonate) at a certain frequency
when excited by an external force, and to keep vibrating after the excitation
is removed. 3. Acoustics. Intensification and prolongation of sound,
especially of a musical tone, produced by sympathetic vibration. 4. Linguistics. Intensification of vocal tones during articulation, as by the air cavities
of the mouth and nasal passages. [AHD]

retro audio Termed coined by Tomlinson
Holman of THX fame, referring to new audio
gear designed using legacy or old technology,
usually tubes, with cosmetics to match.

return loss Category wiring.
The ratio of the transmitted signal strength to the reflected signal strength.
A characteristic often degraded due to excessive bending of the cable.

reverbRecording. Shortened form
of reverberator, or reverberation unit. Any electronic
or acoustical device designed to simulate, or capture, the natural reverberation
of a large hard-surfaced (echoic)
room, and mix it back with the original recorded sound. Reverb today is
accomplished by digital devices using complex DSP algorithms; previously done using
a chamber, a plate, or springs. See: algorithmic reverb and convolution reverb for DSP techniques.

reverberation The total sound field remaining in a room after the original source is
silenced. The length of time of this collapsing sound field is called the
reverberation time and is defined below. Contrast with echo and ambience. "Reverberation represents
the energy decay process after the initial echoes" [Blesser].

reverberation time also RT60 and more often today as T30 Reverberation is all sound remaining after the source stops. The time
it takes for this sound to decay is called the reverberation time,
and it is quantified by measuring how long it takes the sound
pressure level to decay to one-thousanth of its original value. Since
one-thousanth equals a 60 dB reduction,
reverberation time is abbreviated "RT60," however since most acousticians measure the decay time for a 30 dB reduction and then doubles the number to express it as RT60, it is more accurately called T30. Now this is a very simplified definition; for a very thorough discussion see: Averaging RT60 Values for Room-Acoustics by Eric Desart. For most reverberant place in the world see: Inchindown.

reverse mixing Live Sound. A term coined by Rick Chinn of Uneeda Audio who defines it this way:
"Reverse Mixing refers to the practice of listening to
a mix and NOT raising the level of something that you can't hear
sufficiently but instead looking for the source that is masking what
you can't hear and bringing its volume down. This is a good strategy
to avoid Climbing Fader Syndrome."

RF (radio frequency) Broadcast. General
term for radio waves.

RFI (radio frequency interference) A
measure of radio frequency (RF) radiation from equipment. An RF disturbance
is an electromagnetic disturbance having components in the RF range.

RFID (radio frequency identification) Technology using
RF signals to ID individuals. It uses silicon chip tags with radio frequency
functions and on-board memory that holds unique ID numbers, allowing it
to ID and track just about anything.

rhythm The only English language word containing two syllables
with no natural vowels. [Thanks GS.]

rhythm & bluesAbbr. R&B Music. Phrase coined by Jerry Wexler, who would go on to become a famous record producer for Atlantic Records.

RhythmiconBrand name for the first electronic drum machine invented back in 1930(!) by Leon Theremin. Hit the link for the fascinating history.

RIAA (Recording Industry Association
of America) A professional trade organization representing
the U.S. recording industry. RIAA® members create, manufacture
and/or distribute approximately 90% of all sound recordings produced and
sold in the United States.

RIAA equalization curve The standard first proposed by the RIAA
(see above) and adopted by the disc recording
industry in 1953, reaffirmed in 1964 by both the RIAA and NAB and issued as international standard IEC 60098 (old IEC 98) by the IEC,
which remains in effect today. The curve is used in cutting vinyl records
and its inverse is required in phono playback preamplifiers. The curve
attenuates low frequencies and amplifies high frequencies (relative to
a 1 kHz reference point) in order to achieve the maximum dynamic range
for a lateral cut vinyl disc (as opposed to the older method of vertical
cutting). The grooves in a stereo phonograph disc are cut by a chisel shaped
cutting stylus driven by two vibrating systems arranged at right angles
to each other. The cutting stylus vibrates mechanically from side to side
in accordance with the signal impressed on the cutter. The resultant movement
of the groove back and forth about its center is known as groove modulation.
The amplitude of this modulation cannot exceed a fixed amount or "cutover"
occurs. Cutover, or overmodulation, describes the breaking through the
wall of one groove into the wall of the previous groove. Since low frequencies
cause wide undulations in the groove, they must be attenuated to prevent
overmodulation. At the other end of the audio spectrum, high frequencies
must be amplified to overcome the granular nature of the disc surface acting
as a noise generator, thus improving signal-to-noise
ratio.

ribbon
controller (aka pitch ribbon) Synthesizers. A touch-sensitive
strip used to vary pitch. The most popular design is a variable resistor
shaped into a linear controller where the resistance is continuously variable
from one end to another. This form was popularized by Moog synthesizers
in the '60s, but early ribbon controllers date back to the late 1920s with
models by Hellertion, Ondes-Martenot,
and Trautonium.

ribbon microphone Invented by Walter Schottky (the
same German physicist who invented the famous diode) and Erwin Gerlach
of Siemens Halske (German patent number 434855C, December 21, 1924), it is constructed
using a very thin metal foil ribbon (~0.002 mm [really] and pleated
or corrugated to reduce its longitudinal stiffness, to obtain the lowest
resonant frequency so the ribbon is mass-controlled) attached between the
poles of a permanent magnet. The acoustic signal (sound pressure variation)
causes the ribbon to move and interact with the stationary magnetic field
inducing a voltage into the ribbon proportional to the amplitude and frequency
of the audio signal.

Also called velocity microphone or pressure gradient microphone. These names come about from the physical
action of the air particles hitting the ribbon. The motion of the ribbon
is proportional to the velocity of the air particles striking it,
due to its mass being so small that its resonant frequency is infrasonic (2-4 Hz); looked at another way, it responds to the air particle velocity
which is developed by the pressure gradient, i.e., the difference
in air pressure between the two sides of the ribbon (both sides of the
ribbon are open to the atmosphere) causes the ribbon to move.

[Historical Note: In 1931, Harry
F. Olson, along with Frank Massa, successfully
developed the first commercial ribbon microphone based on Schottky &
Halske's patent filed eight years earlier on ribbon loudspeaker and microphone
theory. They received a US patent for the first cardioid ribbon microphone
using a field coil instead of a permanent magnet. Because of this Olson
is usually credited as the inventor of ribbon microphones, even though
this is historically incorrect.]

ribbon tweeter Also invented by Schottky and
Gerlach simply by reversing the physical effects of their microphone; it
is the inverse of the ribbon microphone described
above. It creates a high frequency loudspeaker consisting of a paper-thin metal foil ribbon suspended in a magnetic field
(i.e., placed between the poles of a permanent magnet). The audio voltage
signal drives the ribbon causing a current to flow creating a magnetic
field that reacts with the stationary magnet to create sound proportional
to the applied waveform. Very similar in principle to the dynamic
loudspeaker, only much smaller, with the ribbon replacing the voice
coil and cone arrangement.

Rickenbacker Guitars. Name for the company credited with producing the first commercially
available electric guitar in 1931 (ten years before Les Paul's innovations).
The company was founded by Adolph Rickenbacker (WWI flying legend Eddie
Rickenbacker's cousin) and George D. Beauchamp with the original name
being the Electro String Instrument Corporation.

Ricky Guitars. Popular nickname for Rickenbacker guitars (see above) but a term hated by the founder.

riderLive Sound. A list of items required by a performer, as an attachment (rider) to the main contract, given to the production/touring company. Go here for some outrageous examples.

riff Music. A short rhythmic phrase, especially one that is repeated in improvisation. [AHD] This is an example of an ostinato phrase.

ring it up Phrase coined from the first cash registers that ran
a bell for emphasis when the drawer opened, signifying the end of the calculation.

ring
modulator Synthesizers. An effects generator with two inputs
and one output. The output is the sum and difference frequencies of the
two input signals, and does not contain the original signals — only the
sum and difference signals. These signals are harsh and inharmonious. Input
signals rich in harmonics such as square, rectangular and sawtooth waves
create complex output signals that makes clangor-type,
bell-like sounds.

ring out Acoustics. Shorten
form of "ring out a room," slang meaning for locating and treating a sound
system's resonant and feedback frequencies.

ring-right-red Old mantra from the early telephone days meaning
the ring of a telephone jack always connects to the right terminal, and
is red. Now used by audio designers and installers to remind that the right
channel is always the ring in a 1/4" TRS connector
and the red RCA phono jack and cable.

ring topology A network topology where all nodes are daisy chained
together (connected) in a closed loop.

Riot Fest Music festival featuring "punk/alt. rock/hardcore mayhem," began in Chicago now held in multiple cities in the U.S. and Canada, since 2005.

RISC (reduced instruction set computer) A computer design that achieves high performance by doing the most
common computer operations very quickly, utilizing a high speed processing
technology that uses a far simpler set of operating commands. Primarily
found in workstations and PowerPCs. The
alternative to CISC (complex instruction set computing), the original
way of doing computing.

ritardando Music. Gradually slowing in tempo; retarding.
Used chiefly as a direction. [AHD]

RJ
(Registered Jacks) As in RJ-12 the ubiquitous modular telephone
jack, or RJ-45 the connector and wiring used for connecting Ethernet devices. [Note that the RJ designation specifies both the wiring configuration and the connector. Hit the link for more details.]

RMM (Recreational Music Making) Music making just for the fun of it. It is for those who never thought of themselves as musical and just want to learn and play in a fun manner. Recreational Music Making does not compete with traditional music instruction; it is a alternative concept for playing music. [Think a bunch of naked men in the forest beating drums ... hmm ... maybe not.]

rms powerNo such thing. A misnomer,
or application of a wrong name. There is no such thing as "rms power." Average or apparent power is calculated using rms values but that does not equal "rms power;"
it equals continuous sine wave power output into a resistive load.

road dog Live Sound. Someone always
on the road working as a sound mixer or other live sound jobs. Slang. Homey, homeslice, partner, buddy, cool one, friend, traveling
companion.

roar Acoustics. Term for noise in the 125 Hz to 500 Hz range. [Things like fans and pumps.]

robot 1. A mechanical device that sometimes resembles a human and is capable of performing a variety of often complex human tasks on command or by being programmed in advance. 2. A machine or device that operates automatically or by remote control. 3. A person who works mechanically without original thought, especially one who responds automatically to the commands of others.

Word History: Robot is a word that is both a coinage by an individual person and a borrowing. It has been in English since 1923 when the Czech writer Karel Capek's play R.U.R. was translated into English and presented in London and New York. R.U.R., published in 1921, is an abbreviation of Rossum's Universal Robots; robot itself comes from Czech robota, "servitude, forced labor," from rab, "slave." The Slavic root behind robota is orb-, from the Indo-European root *orbh-, referring to separation from one's group or passing out of one sphere of ownership into another. This seems to be the sense that binds together its somewhat diverse group of derivatives, which includes Greek orphanos, "orphan," Latin orbus, "orphaned," and German Erbe, "inheritance," in addition to the Slavic word for slave mentioned above. Czech robota is also similar to another German derivative of this root, namely Arbeit, "work" (its Middle High German form arabeit is even more like the Czech word). Arbeit may be descended from a word that meant "slave labor," and later generalized to just "labor." [AHD]

rock and roll (seen more often as rock 'n' roll)
In 1922, the words "rock" and "roll", which were black slang for sexual intercourse, appear on record for the first time, Trixie Smith's "My Man Rocks Me (With One Steady Roll)". [Rock 'n' roll Timeline 1877-1959] [Note: Alan Freed did not create the phrase, he just applied it to a (then) new music genre.]

Rockestra "Rockestra is a music experience of epic proportions! The super group was founded by world-renowned cellist, Buffi Jacobs of Polyphonic Spree and is known for their high energy and dynamic performances. Rockestra incorporates vast musical knowledge and instrument mastery into a truly unique musical experience for every audience. The group is available as a duo, trio, quartet or a full on rock ensemble." [From webvsite.]

rock harmonicon (aka stone dulcimer or geological piano) A xylophone-like musical instrument constructed from stone, typically slate. One famous example is Joseph Richardson's creation residing in the Keswick Museum and Art Gallery in Cumbria, England, constructed over thirteen years in the nineteenth century. [See Cox (p. 68) for more details.]

Rock on the Range Music festival held yearly in Columbus, OH, since 2007. Motto: "Where Rock Lives."

Rogowski coils Electronics. (after Walter Rogowski) A type of current transformer
used for measuring alternating current or high-speed current pulses through a conductor.

RoHS (Restriction of Certain Hazardous Substances) European directive
restricting the use of hazardous substances in electrical and electronic
equipment. See WEEE.

rolloff rateFilters. The rate
at which low-pass, high-pass and bandpass filters attenuate
frequencies outside the passband. Expressed
in dB/octave, it is a measure of the attenuation slope. Slopes occur in
6 dB/octave increments (due to the natural storage effects of capacitors
and inductors), e.g., 12 dB/oct, 18 dB/oct, 24 dB/oct, etc.

ROM (read-only memory) A memory from which data, after
initial storage, may only be read out, but new data cannot be written in.
The normal audio CD is an example of a read-only system.

room modes or eigentones (from
German eigen meaning "self" or "own") Acoustics. The acoustic resonances (or standing waves) in a room
(or any enclosed space) caused by parallel surfaces. It is the dimensional
resonance of a room, where the distance between the walls equals half the
wavelength of the lowest resonant frequency (and resonates at all harmonic
frequencies above it). Room modes create uneven sound distribution
throughout a room, with alternating louder and quieter spots. See room
ratios below.

room
ratios Acoustics. The ratios of dimensions for a rectanguloid
room recommended to ensure a uniform distribution of low-frequency room
modes (see above). There are standards (few) and there are disagreements
(many). See link for overview and details. A rough summary follows:

(1.1 x W/H) less than or equal to (L/H) less than or equal to [(4.5 x W/H)
- 4]

L/H less than 3.0 and W/H less than 2.0

L=length, W=width and H=height

root mean square Abbr. rms (lowercase) Mathematics. The square root of the average of the squares of a group
of numbers. [AHD] A useful and more meaningful
way of averaging a group of numbers.

rosenfeld A proposed unit defined as electricity savings of 3 billion kilowatt-hours a year, i.e., equivalent to the amount generated by a 500-megawatt coal-fired plant in one year. After Arthur H. Rosenfeld, who is referred to as the godfather of energy efficiency.

Rosie DJ Mixers. First stereo DJ mixer developed by Alex
Rosner, named after the designer and for its red paint. [Alex Rosner was one of those lucky few on Schindler's List, and Oskar Schindler attended his high school graduation.In the movie he is portrayed as the young blond boy who jumped down into the sewage in the outhouse and peaked through a knot hole as the Nazi's marched by. Thanks, Todd Peden! ]

Roskilde Festival Billed as the largest music festival in Northern Europe; and since its beginnings in 1971 is held in Roskilde, Denmark. The Roskilde Foundation donates all profits to charity.

rotary equalizer A multi-band variable equalizer using rotary
controls as the amplitude adjustable elements. Both active and passive
designs exist with rotary controls. Center frequency and bandwidth are
fixed for each band.

routerAudio. An audio device used to selectively
assign any input to any output, including the ability to add inputs together.
In this way, one input could go to all outputs, or all inputs could go
to just one output, or any combination thereof. An n x m matrix forms the core of any router, where there are n inputs and m outputs. Typically, level controls are provided on all inputs and outputs;
balanced and unbalanced designs exist. More elaborate designs are called matrix-mixers. Networks. Wired or wireless network routers are devices that connect multiple networks. Also see: gateway.

RS-232 The standard serial interface (EIA/TIA-232-E)used
on most personal computers. A format widely supported for bidirectional
data transfer at low to moderate rates. The most common interface method
used to connect personal computers with peripheral hardware and instruments.
Use is restricted to one peripheral at a time and short distances. The
standard originally called for DB-25 connectors,
but now allows the smaller DB-9 version.

RS-485 The standard describing the electrical
characteristics of a balanced interface used as a bus for master/slave
operation. Allows up to 32 users to bridge onto the line (as opposed
to RS-422's need to daisy-chain the interconnections). Same as EIA-485.
[See AN 759 for RS-422 vs. RS-485 comparison.]

RS-490 The standard adopted in 1981 by the EIA entitled Standard Test Methods of Measurement for Audio Amplifiers.
The power amp testing standard for consumer products.

rubato Music. Rhythmic flexibility within a phrase or
measure; a relaxation of strict time. [AHD]

Rube Goldberg(1883-1970) American cartoonist famous for his contraptions that accomplished something very simple in extremely complicated ways. His name is recognized as an adjective defined as: "Of, relating to, or being a contrivance that brings about by complicated means what apparently could have been accomplished simply." [AHD]

rubidiumA soft silvery-white metallic element of the alkali group that ignites spontaneously in air and reacts violently with water, used in photocells and in the manufacture of vacuum tubes. [AHD] Used in pro audio applications to create the most precise and stable atomic audio clocks for recording studios. See for example Stanford Research Systems Perfection 10.

rumble Acoustics. Term for noise in the 31.5 Hz to 125 Hz range. [Air turbulence, for example.] Phonographs. A quantitative measure of phonograph
turntable noise and vibration resulting from performance imperfections.
The rms voltage is measured at the cartridge while playing
a blank (silence) record, and the answer expressed in dB below a reference point.

ruthenium Chemistry. SymbolRu
A hard silver-gray acid-resistant metallic element that is found in platinum ores and is used to harden platinum and palladium for jewelry and in alloys for nonmagnetic wear-resistant instrument pivots and electrical contacts. Atomic number 44; atomic weight 101.07; melting point 2,310°C; boiling point 3,900°C; specific gravity 12.41; valence 0, 1, 2, 3, 4, 5, 6, 7, 8. [AHD] In audio world it is found in the Ultrasone Edition 8 headphones used as a coating on the outer ear cups.

RW 232 (also RaneWare) A trademark of Rane Corporation used
to identify Rane's RS-232-based variant of the PA-422 AES standard.

RYTMO (Reaching Youth Through Music Opportunities) "An after school music program designed to provide a positive, creative and professional environment for underserved youth who demonstrate musical, technical and/or business potential in the arts."

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